Hinged plastic lids are used on packages for a variety of products. Packages with hinged plastic lids are popular with consumers because they provide a convenient means for opening and closing the packages. Additionally, the plastic lids can improve the protection of the product contained with the package by providing a moisture barrier and good seal. Furthermore, it is common for packages with hinged plastic lids to provide a means to secure the lids in the closed position. Typically, the securing means is a latching system which is molded or formed in mating plastic parts.
The ability to mold or form polymeric materials permits convenience, sealing, latching, and other features to be built into the hinged plastic lids. However, the high cost of polymeric materials relative to paperboard may warrant the selection of paperboard material for the basic containment and delivery functions of a package. Combining a hinged plastic lid with a paperboard carton is a way of providing the convenience and other features of a plastic lid with the economy of a paperboard carton.
One method for applying a hinged plastic lid to a paperboard carton is to first attach a plastic frame to an open end of a carton. The plastic lid which is either integrally or otherwise attached to the frame at the hinge can be closed against the frame for sealing. An example of such an arrangement is disclosed in U.S. Pat. No. 3,944,127 issued to Bruke et al. on Mar. 16, 1976.
The prior art also teaches that a latching system may be incorporated in such plastic frame and hinged lid arrangements for the purpose of securing the hinged plastic lid in the closed position. The latching system may be produced by molding a boss on the lid at a location whereupon closing the lid the boss will snap into a receiving cavity molded into the plastic frame. Unfortunately, the plastic frame is normally as large or larger than the lid and may cost as much as the plastic lid.
A second method for applying a hinged plastic lid to a paperboard carton is to close the lid directly against the edges of an open end of the paperboard carton, thereby eliminating the need and expense of a frame. An example of this arrangement is also disclosed in the aforementioned U.S. Pat. No. 3,944,127 to Bruke et al. With this arrangement, typically either gravity or friction about the overlapping surfaces of the lid against the carton maintains the lid in the closed position. However, this arrangement, without the benefit of a mating plastic part such as a frame, has not provided the desirable feature of a latching system.